JPS6028294A - Printed circuit board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printed circuit board, and particularly to a printed circuit board with an improved structure of a soldering land formed at the tip of a conductor pattern for fixing chip-type electronic components by soldering.

1 and 2 are a plan view and a front view showing a typical example of a chip-type electronic component mounted on a printed circuit board, which is the object of the present invention. As is clear from FIGS. 1 and 2, the chip-type electronic component 1 consists of an electronic component element 2 and N poles 3 and 4 formed at both ends of the electronic component element 2. The general size of such an electronic component 1 is shown in the table below.

Conventionally, in order to fix a chip-type electronic component 1 as described above to a printed circuit board and connect it to a conductive pattern formed on the printed circuit board by soldering, it has been soldered integrally with the conductive pattern on the printed circuit board. An attached land was formed. 3 and 4 are plan views showing soldering lands of a conventional printed circuit board and chip-type electronic components fixed to the soldering lands.

Referring to FIG. 3, chip type electronic component 1 was mounted on a printed circuit board by the following procedure.

First, a conductive pattern 5.6 formed on a printed circuit board.
An adhesive is applied onto the insulating portion between the soldering lands 7 and 8 formed integrally with the soldering land 7 and 8, and then the chip type electronic component 1 is temporarily fixed with this adhesive. Finally, the electrode 3.4 of the chip type electronic component 1 and the soldering land 7.8 are soldered by flow soldering.
and solder.

By the way, in the conventional soldering land 7.8 shown in FIG. 3, its width is formed narrower than the width of the electrode 3.4 of the chip-type electronic component 1, while in the example shown in FIG. The width of the attached land 7.8 is the electrode 3 of the chip type electronic component 1,
It is formed wider than the 4th cup. This selection of solder land widths has caused the following problems with conventional printed circuit boards.

FIG. 5 is a plan view showing the state in which the chip type electronic component 1 is soldered to the printed circuit board having the soldering lands shown in FIG. 2 by flow soldering. As is clear from FIG. 5, when the width of the soldering land 7.8 is made narrower than the width of the electrodes 3 and 4 of the chip-type electronic component 1,
There is a problem in that the solder 9 does not adhere well to the edge portions 4 and therefore a reliable connection cannot be obtained. Furthermore, when the chip-type electronic component 1 is displaced from a predetermined temporary fixing position, there is also a problem in that excess solder adheres to the corner portions.

On the other hand, the width of the soldering land 7.8 is
In the case where the width of the electrode 3.4 is wider than the width of the electrode 3.4 (the example shown in FIG. 83), as shown in the same plan view in FIG.
Although the connection between 3.4 and conductor patterns 5 and 6 is good,
Since a large amount of solder is attached, there is a drawback that the chip-type electronic component 1 is easily damaged by external forces such as bending.

Furthermore, as is clear from both FIGS. 5 and 6, in the conventional solder land, when the chip-type electronic components 1 are arranged in parallel, the solder flows in the direction of the arrow X. Another drawback was that bridges were not formed between the soldering lands.

Therefore, an object of the present invention is to eliminate the above-mentioned drawbacks, to be able to reliably connect a conductive pattern and an electrode of a chip-type electronic component with a small amount of solder, and to prevent the occurrence of bridging and the destruction of electronic components. It is an object of the present invention to provide a printed circuit board on which soldering lands of a novel shape are formed, which can reliably prevent such problems.

In summary, the present invention provides that the planar shape of a soldering land has a width at its maximum width that is approximately equal to the electrode width of a chip-type electronic component, and a portion closer to the chip-type electronic component than the maximum width. This is a printed circuit board in which the width of the conductor pattern is narrower than the width of the chip-type electronic component, and the part of the widest part on the conductor pattern side is approximately semicircular.

Other features of the invention will become clear from the following description of embodiments with reference to the drawings.

FIG. 7 is a plan view showing an embodiment of the present invention. Referring to FIG. 7, in this embodiment, soldering land 17
．． 18 is formed in a circular shape.

The width of the maximum width portion of this soldering land 17.18, that is, the diameter φD, is selected to be equal to the width of the electrode 3.4 of the chip type electronic component 1. For example, the three shown in the table above
, for a chip-type electronic component with a size of 2 x 1.6 mm, the diameter φD is 1.6 to 1.7 + un, and the diameter is 2 x 1.25 m.
If the size is m, the diameter φl1tl, 25~1
, 35mm. In addition, each soldering land 17.18
Distance between centers is 1m! tP is 3°75 mm for a chip type electronic component with a size of 3°2 x 1.6 mm, and
．． In the case of 25 mm, it is 2.5 mm.

The chip-type electronic component 1 of this embodiment can be mounted on the printed circuit board by the same method as the conventional method described above. That is, after first temporarily fixing with adhesive, soldering is performed using flow soldering.

However, as will be discussed in more detail below, the embodiment shown in FIG. 7 effectively overcomes the problems associated with conventional printed circuit board soldering lands.

FIG. 8 is a plan view showing the soldering state in the embodiment shown in FIG. 7 when chip-type electronic components connected in the vertical direction are arranged in two rows. Here, as shown on the right side, even if the chip type electronic component 1 is misplaced despite being temporarily fixed, no excess solder will remain on the soldering lands 17 and 18. This is because the soldering lands 17 and 18 are circular and do not have any extra corner portions. Furthermore, no bridge occurs between the soldering lands 17, 17 and 18, 18 that are adjacent in the horizontal direction in FIG. This is because soldering land 17.
This is because since the solder 18 is circular, the surface tension of the solder 19 can act more effectively.

The above-mentioned advantages are more pronounced in the arrangement shown in plan view in FIG. In FIG. 9, two electronic components 1°1 arranged in series in the vertical direction are arranged in two rows. Here, as illustrated in FIG. 9, bridging is likely to occur in the portion where the four soldering lands 17, 17, 18, and 18 are close to each other, that is, in the central portion of FIG. However, here 1. Since each soldering land 17, 18 is formed in a circular shape, the solder 19 is effectively pulled toward the center of the circle by surface tension as described above, thus reliably preventing the occurrence of bridging, and reducing the amount of solder. It is also possible to keep it to a small amount. That is, the advantages of the embodiment shown in FIG. 7 described above are particularly noticeable in the arrangement shown in FIG. 9.

Also, when designing this type of printed circuit board, 2.5
A basic grid with mm pitch is used. therefore,
The soldering lands 17 and 18 of this embodiment are placed on this basic grid or 1/2 of the basic grid, that is, 1.25 m1l.
By arranging it on an auxiliary grid of l pitch, it is possible to create a design drawing extremely easily.

In addition, in the embodiment described above, the circular soldering land 17
．． 18 (FIG. 7), the soldering land of the present invention is not limited to this shape. For example, the first
As shown in the same plan view in Figure 0, the part on the chip type electronic component 1 side from the maximum width part is made into a trapezoid with a tapered tip.
On the other hand, the portion on the side of the conductor patterns 5 and 6 from the maximum width portion may be formed in a semicircular shape. Here again, the maximum width of the soldering lands 17.degree. 18 is selected to be equal to or slightly larger than the width of the electrodes 3.4 of the chip-type electronic component 1. Further, as shown in a plan view in FIG. 11, the soldering lands 17 and 18 may be formed in the shape of a rectangle or square with the four corners largely rounded to form an arc. In the example of FIG. 11, soldering lands 17 and 18
The maximum width part of is selected to be equal to the width of the electrodes 3 and 4 of the chip type electronic component 1, and the part on the chip type electronic component 1 side of the maximum width part is formed narrower than the width of the electrodes 3 and 4. has been done. In addition, in the example shown in FIG. 11, the part on the conductor pattern 5.6 side from the maximum width part of the soldering land 17.18 is also formed in the same shape as the part on the chip type electronic component 1 side. , large (it can be said to have an approximately semicircular shape because the corners have been cut).

As described above, according to the present invention, the planar shape of the soldering land has a width at its maximum width that is approximately equal to the electrode width of the chip component, and a portion from the maximum width toward the chip-type electronic component. It is formed narrower than the electrode width of a chip-type electronic component, and the part on the conductor pattern side from the widest part is formed in a roughly semicircular shape, so the surface tension of the molten solder acts extremely effectively. It is possible to reliably prevent excess solder adhesion and the occurrence of bridges, which were problems in the past, and since there is less solder on the electrodes of chip-type electronic components, it is also effective in reducing destructive stress on electronic components. It becomes possible to absorb into.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an example of a chip-type electronic component mounted on a printed circuit board, which is the customer of this invention. FIG. 2 is a plan view of the chip-type electronic component shown in FIG. FIG. 3 is a front view. FIGS. 3 and 4 are plan views showing the relationship between the soldering land and the chip-type electronic component in the soldering land slot of a conventional printed circuit board. FIG. 5 and FIG. FIG. 6 is a plan view showing the state of soldering in the conventional printed circuit board shown in FIGS. 3 and 4.
The figure is a plan view for explaining one embodiment of the present invention. 8 and 9 are plan views showing a state in which chip-type electronic components are soldered using the embodiment shown in FIG. 7. FIG. FIGS. 10 and 11 are plan views showing other examples of the shape of the soldering land of the present invention. 1... Chip type electronic component, 3, 4... Electrode of chip type electronic component, 5.6... Conductor pattern, 17.18.
...Soldering land, 19... is /υ. Agent Masu Oiwa Iken 3 Figure 4 Figure 5 Figure 6 Figure 10 Procedural amendment (voluntary) 2. Name of the invention Printed circuit board 3. To the representative of the person making the amendment Hitoshi Katayama 5. Column 6 of Detailed Description of the Invention of the Specification Subject to Amendment, Contents of the Amendment (1) "1.
``From Figures 1 and 2'' has been corrected to ``From Figures 1 and 2''. (2) In the 10th line of page 5 of the specification, the phrase ``(in the example shown in FIG. 3)'' should be corrected to ``(in the example shown in FIG. 4)''. that's all

Claims (4)

[Claims] (1) In a printed circuit board in which a soldering land is formed at the tip of a conductor pattern in order to fix a chip-type electronic component by soldering, the planar shape of the soldering land is such that the maximum width is the electrode width of the chip component. , and the portion on the chip component side from the maximum width portion is formed narrower than the electrode width of the chip component, and furthermore, the portion on the conductor pattern side from the maximum width portion is approximately semicircular. A printed circuit board characterized in that it is formed so as to be. (2) The printed circuit board according to claim 1, wherein the soldering land has a circular planar shape. (3) The soldering land mentioned above may be used in accordance with the design.
The printed circuit board according to claim 1 or 2, which is arranged on a basic grid of 111111. (4) The soldering land is used in 1.
A printed circuit board according to claim 1 or 2, arranged on a 25 mm auxiliary grid.